In the prior art, a vacuum apparatus adapted for use in a commercial environment, such as a self-service type car wash or the like, usually comprises a vacuum motor contained within a housing. The housing is typically constructed from fiberglass, or from sections of sheet metal or the like that are bolted or welded together.
One such vacuum apparatus, shown by Livingston, U.S. Pat. No. 4,036,346, comprises a molded fiberglass housing secured to an L-shaped base member constructed from tubing. This type of vacuum apparatus has several disadvantages. The fiberglass housing is susceptible to cracking and breaking, as when inadvertently struck by a vehicle or the like using the apparatus, thereby resulting in loss of the vacuum force produced within the housing. In addition, repeated exposure to the weather fades or discolors the fiberglass housing thereby requiring periodic maintenance such as painting or the like. Finally, the housing and the associated base member, being relatively light and easily transportable, is therefore susceptible to being stolen.
Another vacuum apparatus, shown by Foster, U.S. Pat. No. 3,320,725, has a housing in the form of a tank having a motor therein with the tank being affixed to a wall. This apparatus has the same disadvantages with respect to damage and the loss of vacuum force as discussed above. In addition the relatively small thickness of the sides of the tank coupled with the close proximity of the vacuum motor to the sides of the tank produce an apparatus which is loud and one not well adapted for use in areas where it is desirous to minimize excessive noise.
The present invention overcomes these problems of the prior art. By providing a fiberglass inner shell enclosed by a monolithic outer housing formed from concrete, an essentially airtight vacuum apparatus is produced requiring little or no exterior maintenance. The outer housing is particularly well adapted to withstand the inadvertent contact from the vehicles using the apparatus without the loss of the vacuum pressure within the inner shell. By disposing a plurality of door means on the housing each adapted to extend through the housing and into the inner shell, the vacuum apparatus of the present invention may be quickly and efficiently cleaned and the vacuum motors easily serviced. In addition, the concrete outer housing efficiently attenuates the noise produced by the vacuum motors thereby producing an apparatus which is relatively quiet during operation. Finally, the concrete housing having a considerable weight and mass produces a vacuum apparatus which is not susceptible to being stolen.